package com.peng.tree.foreach;

import com.peng.tree.Node;

/**
 * 对树结构的深度优先遍历
 * 递归版本
 */
public class DeepForEach_Recursion {

    public static void pre(Node head) {
        if (head == null) {
            return;
        }
        System.out.println(head.value);
        pre(head.left);
        pre(head.right);
    }

    public static void mid(Node head) {
        if (head == null) {
            return;
        }
        mid(head.left);
        System.out.println(head.value);
        mid(head.right);
    }

    public static void post(Node head) {
        if (head == null) {
            return;
        }
        post(head.left);
        post(head.right);
        System.out.println(head.value);
    }

    public static void main(String[] args) {
        Node node = new Node(1);
        Node node2 = new Node(2);
        Node node3 = new Node(3);
        Node node4 = new Node(4);
        Node node5 = new Node(5);
        Node node6 = new Node(6);
        Node node7 = new Node(7);
        Node node8 = new Node(8);
        Node node9 = new Node(9);

        node.left = node2;
        node.right = node3;
        node2.left = node4;
        node2.right = node5;
        node3.left = node6;
        node3.right = node7;
        node4.left = node8;
        node4.right = node9;
        /*
                   1
             2              3
           4   5         6     7
         8   9

         */

        pre(node);


    }
}
